Crystal diode



I April 1958 D. BAKALAR 2,832,016

CRYSTAL DIODE Filed Nov. 22. 1954 CRYSTAL DIODE David Bal alar, Boston, Mass. Application November 22, 1954, Serial No.470,408

4 Claims. (Cl. 317-236) ker is connected to the other face.

The present invention relates particularly to the meth- 0d of construction and the combination of crystal and cat whisker used in forming the diode or rectifier.

In the present invention the method and means of con-' struction provide an exceedingly rugged crystal transistor which gives faithful performance and constant characteristic conditions which may be reliably established in manufacturing specifications and under operating conditions.

One of the features of the present invention is that the cat whisker,- so called, forms a permanent connection with the germanium or other type of crystal which ma be used in the nature of eutectic alloy junction which is sealed and permanent and will not under ordinary con ditions pull loose or free from the crystal itself.

In addition to this, the crystal and the connecting cat whisker are so selected with regard to added impurities to enhance the reliability of the elements when used as a rectifier or transistor in the usual electric circuit.

A further feature of the present invention is that in the construction of the diode or crystal rectifier, the lead in wires have glass beads formed thereon prior tothe insertion of the diode elements into the casing so that all that is necessary is to seal the bead into the casing which makes it possible to attach the electrodes under conditions of lower temperature than otherwise would be possible.

Other and further advantages will be more readily understood from the description in the'specification set forth below when taken in connection with the drawings, in which:

Figure 1 shows an exploded view of the elements forming the diode or rectifier of the present invention, and,

Figure 2 shows a section through the complete diode.

In the drawing of Figure 1, 1 illustrates a glass vessel. 2 is a conductor with a glass bead 3 mounted on it. 4 is a conductive mounting plate, and 5 is a germanium silicon or other type crystal. h

At the top section of the drawing of Figure 1, there is shown the upper connector 6 and the cat whisker 8, preferably made of gold or aluminum wire with added impurities of the third or fifth column of the periodic table. If the impurities of the third column are used, impurities would comprise indium, gallium, aluminum or some other similar element. If impurities of the fifth column were used, they maybe antimony or arsenic or some other equivalent elements.

The cat whisker" 8 is welded at one endto the conductor 6 and is preferably formed with a spring bend 9 to allow for adjustment to the face of the crystal 5. The crystal 5 is preferably made of germanium, silicon or some other crystal material with added impurities of a 2,832,016 Patented A r. a2, 1958 icedifferent periodic column than the impurity used in the catwhisker, that is, if the impurity in the cat whisker is of column 3 of the periodic table, that in the crystal crystal itself, provides an improved construction and operation of the diode crystal, particularly when the wire is actually fused orsealed to the crystal as in the present invention. Not only is the fusing readily accomplished,

but the reliability of connection and performance is greatly improved in this combination. 1

In Figure 1, elements 2, 4, 6 and 8areall conductors and the element 5, the crystal, is a so called semi-conductor. In putting the diode together, the bead 3 is first sealed to the. conductor 2 and then the conductor and the bead 3 are sealed into the lower end of the tube 1 by fusing the bead directly to the wall ofthe tube 1 on its inner side. j

The conducting plate 4 may be mounted on the upper end of the conductor 2 as viewed in Figure 1 prior to the sealing of the bead and the conductor in the tube or the conducting plate 4 maybe soldered to the end of the conductor 2 when it is inside the tube.

-However it is not desirable to attach the germanium crystal or the crystal 5 to the plate 4 has been fused to the tube.

. A low melting pointsolder is used to attach the crystal 5 to the conducting plate 4 after the bead-3 and plate 4 have been put in place. With the crystal then fixed in place the conductor 6 with the bead 7 and the cat whisker 8 already attached to thecondu'ctor is inserted in the top end of the glass casing 1 and the bead is sealed in the end of the casing or tube as shown in Figure 2.

The end of the cat whisker 8 with its spring bend 9 formed in it'is forced against the surface of the crystal and sealed into the crystal surface in a permanent joint. The sealing of the end of the cat whisker into the surface of the crystal forms a solid eutectic alloyed junction 7 of the permanent type which remains in the same position at all times. I

The cat whisker 8 is preferably formed of a gold or aluminum wire and has impurities preferably of the periodic tables of the fifth column, among which preferably are antimony and arsenic. With this type of impurity used in the gold or aluminum cat whisker, the crystal itself should have impurities of the third column, such as indium, gallium or aluminum for the best operating combination for the crystal.

Fusing of the cat whisker to the surface of the germanium crystal may be accomplished by a current passed through the cat whisker and crystal after the construction has been completed.

The case is of course hermetically sealed by sealing the beads in the ends of the tube and theheating of the tube prior to the sealing of the beads in the tube exhaust substantially sufiicient air in the tube so that it is not necuntil after the bead Having now described my invention, I claim: 1. A method of manufacturing an enclosed crystal diode which comprises forming on a conducting wire a glass bead adapted to fit into one end of an enclosing vessel of glass, fusing the wire with the bead formed thereon in said end of the tube, then heat sea-li'ng a crystal electrode on the end of the conductor in the tube, after which a second conducting wire with a bead mounted thereon is fused in the 0th-; end of the tube with a cat Whisker metallic conductor extending from said second conductor and fused to the surface of the crystal.

2. A crystal diode comprising an enclosing glass vessel, a conductor extending through each end of the vessel to the inside thereof, a bead formed on the conductors for sealing the conductors inthe vessel, a conductive mounting plate mounted at the end of one conductor, a crystal mounted on said plate within the enclosing vessel, a cat whisker conductor Welded to the other conductor Within the tube, said cat whisker being fused to the surface of the crystal at the end of the cat whisker.

3. A method of manufacturing an enclosed crystal diode which comprises forming on conducting wires, glass beads adapted to fit into each end of an enclosing vessel, fusing one Wire with a bead thereon into one end of the vessel, then soldering a crystal electrode on the inner m d of. the th vesse i s rting a second gla s bead in the other end of the vessel with a conducting wire having a cat whisker attached thereto in contact with the electrode at the end of the wire within the tube.

4. A diode crystal construction comprising an enclosing glass vessel having a conductor fused in one end of the glass vessel with'a bead forming a part of the end thereof, a conductive mounting plate fixed to the end of the conductor, a germanium crystal soldered to said mounting plate within the vessel, a second conductor extending through the opposite end of the glass vessel with a bead thereon fused to the walls of the glass vessel forming the end seal ofthe glass vessel, said second conductor having a cat whisker bearing on the germanium crystal surface and fused thereto.

References Cited in the file of this patent UNITED STATES PATENTS 2,633,489 Kinman Mar. 31, 1953 2,693,555 North et al Nov. 2, 1954 2,694,168 North et a1. Nov. 9, 1954 2,704,818 North Mar. 22, 1955 2,705,768 Kleimack et a1. Apr. 5, 1955 2,795,743 Lehovec June 11, 1957 

